A ‘wireless LAN’ is configured to provide communication services, such as the Internet, to wireless terminals (e.g., a Personal Digital Assistant (PDA), a notebook computer, and so forth) placed within a certain distance from a location where an Access Point (AP) is installed. The wireless LAN had the range of coverage of at most ten (10) meters at the early stage, but, in the 2000s, the range of coverage has widely expanded from fifty (50) meters to several hundreds of meters. Furthermore, the transmission speed of the wireless LAN has also been increased and is able to transmit and receive high-capacity multimedia. Accordingly, the wireless LAN can be used to supply a high-speed data service to subscribers who are in buildings such as schools, airports, and hotels.
As the wireless LAN service is commercialized, a terminal in which a mobile communication terminal and a Wireless Fidelity (Wi-Fi) terminal providing the wireless LAN service are mixed together has been developed. A terminal capable of using both the wireless LAN service and the mobile communication service is called a ‘dual mode terminal’.
The dual mode terminal includes a wireless LAN module for the wireless LAN service and a mobile communication module (e.g., CDMA module) for the mobile communication service. In case the dual mode terminal enters a wireless LAN service coverage, it operates in a wireless LAN service mode, whereas the dual mode terminal gets out of the wireless LAN service coverage, it operates in the mobile communication service mode. When the dual mode terminal enters or gets out of the wireless LAN service coverage, the operation mode of the terminal is switched. Here, the switch of the terminal can be manually performed by a user or can be automatically performed.
The dual mode terminal periodically scans accessible APs and accesses a scanned AP, such that the operation mode of the dual mode terminal is automatically switched. The scan period can be variably set from a short period of several tens of seconds to a long period of several minutes. If the scan period is set to be short, the access time to the AP can be reduced as scan results can be known quickly. However, a problem can occur wherein the battery power is quickly consumed as the power consumption increases due to frequent scanning.
Conversely, if the scan period is set to be long, the power consumption can be reduced to increase the battery usage time. However, a problem can occur wherein the access time to the AP can be increased.
A portable terminal has a limited battery power. Thus, if the power consumption is great, there exists an inconvenience that the user has to frequently charge the battery or replace the battery with another battery. Further, if the scan period is set to be long so as to reduce the power consumption, the efficient network access cannot be performed due to the AP access time delay.
Accordingly, there exists a necessity of a method for accessing a wireless LAN capable of reducing power consumption with reducing the access time to an AP.